1. Field of the Invention
The present invention relates to the detection, tracking and recognition of a target object, and more particularly, to a system and method for calculating a signature for recognition of a target object.
2. Discussion of the Related Art
The detection and tracking of a target object is typically accomplished with radio detection and ranging, commonly known as radar. Radar systems typically emit electromagnetic energy and detect the reflection of that energy scattered by a target object. By analyzing the time difference of arrival, Doppler shift, and various other changes in the reflected energy, the location and movement of the target object can be calculated.
Due to various advantages, microwaves are primarily used in modern radar systems. Microwaves are particularly well suited for radar due to their lobe size. Beamwidths of a microwave signal may be on the order of 1 degree, with wavelengths of only a few centimeters.
Radar systems for target detection and tracking are typically monostatic, meaning the radar has both the receiver and transmitter at the same location. A pulse based radar system scans a field of view and emits timed pulses of energy; therefore, a window exists between each scan and pulse where there is no signal and no ability to determine the existence or location of a particular object. The inability to continually track a target object raises the chance that a tracking system will generate inconsistent information among each sampling of data. The inclusion of scanning mechanisms and high-energy RF power transmission also tend to increase the cost of construction and operation of a radar system.
In addition to the ability to detect and track a target object, additional information, such as the identification of the target object, or identifying information, known as the signature of the target object, may also be useful in various environments. For example, during military operations, the determination of an object as friendly or foe is of great importance.
Various technologies, such as Jet Engine Modulation (JEM) and Inverse Synthetic Aperture Radar (ISAR) have had some success in creating useful signatures for target objects. JEM is the detection of the signal modulation created by the reflection of the radar beam off the moving parts of the jet engine. This technique is useful only when the target object is at an aspect angle that allows this phenomenon to be detected. ISAR creates a two-dimensional map of the target object by using a large bandwidth transmitted signal.
As discussed earlier, a target illuminated by a microwave, monostatic radar has a large number of narrow lobes. These lobes are influenced and scattered by the detailed structures of the target object. The scattering of the lobes limits the amount of energy reflected back to the radar's receiving antenna.
Whether using JEM, ISAR, or some other signaturing method, at microwave frequencies, current signaturing systems must calculate and process large numbers of narrow, weak lobes of electromagnetic energy influenced by the fine details of a target object. These calculations will typically be done at intervals that allow for substantial movement of the target object between each calculation, adding significant complexity to the determination of the identity of the target object.
These and other deficiencies exist in current object recognition systems. Therefore, a solution to these problems is needed, providing an improved object recognition system specifically designed to more simply and accurately identify signature features of a target object.
Additional features and advantages of the invention will be set forth in the description that follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof, as well as the appended drawings.